Method and apparatus for neutralizing fatty oils



Aug. .19, 1958 J. WIJNBIIERG I I ,4

METHOD AND APPARATUS FOR NEUTRALIZING FATTY OILS Filed March 2a. 1955 '5Sheets-Sheet 1 :B/IZ

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INVENTOR. Jan Yl/ijn berg Aug. 19, 1958 J. WlJNBERG 2,343,468

METHOD AND APPARATUS FOR NEUTRALIZING FATTY OILS Filed March 28, 1955 5Sheets-Sheet 2 Fig.2

/N VE N TOP. Jan Z/l'jnberg Aug. 19, 1958 J. WIJNBERG METHOD ANDAPPARATUS FOR NEUTRAL-IZING FATTY OILS 3 Sheets-Sheet 5 Filed March 28,1955 II I I I II IIV I Unite tales METHOD AND APPARATUS FOR NEUTRALIZINGFATTY OHJS Jan Wijnberg, Wormerveer, Netherlands, assignor toAktiebolaget Separator, Stockholm, Sweden, 21 .corporation of SwedenApplication March 28, 1955, Serial No. 497,084

8 Claims. (Cl. 260-425) this chamber filled with oil during the feeding,the lye being led directly into and mixed with the oil mass rotatingwith and filling the chamber, feeding the resulting mixture into theseparating chamber of the centrifugal bowl to divide it into oil andsoap, and separately discharging the oil' and soap from the centrifuge.

The apparatus disclosed in the above-mentioned patent applicationconsists of a centrifuge, including a centrifugal bowl rotatable on avertical axis and having a separating chamber provided with separateoutlets for oil and neutralization products, a hollow spindle extendingfrom the bowl and forming a rotating feed chamber opening directly intotheseparating chamber, a fixed reagent supply tube extending through thehollow spindle into the feed chamber, an oil supply tube fixed insurrounding relation to the first tube and forming therewith an oilpassage, and means forming an hermetically sealed passage between theoil supply tube and the outer por- 7 tion of the bowl spindle.

The results stated in said patent application have been obtained on apilot plant scale, but when treating fatty oils having a high percentageof free fatty acids on a factory scale, the results have not been quitesatisfactory.

I have found that when treating oils having a high percentage of freefatty acids on a factory scale, substantially improved refining results(a better degree of neutralization) are obtained in the method referredto above by heating the oil and possibly the lye prior to theneutralization operation, passing the oil-lye mixture for a period oftime of less than a second in turbulence-producing passages through therotating chamber, and feeding the mixture immediately from this chamberto the separating chamber.

When refining fatty oils with alkali, it is desirable to obtain anabsolutely neutral oil while keeping the saponification losses low. Tothis end, it is essential to effect an intense neutralization during avery short period of contact between the oil and the alkali so as toavoid undesired saponification of the oil. In order to obtain a completeneutralization, an excess of alkali must be used.

In the method disclosed in the above-mentioned patent application, lyeat room temperature is mixed with the oil at a temperature of 85 C. andthe period of contact between the oil and lye is about one second. Inthe improved method, however, it has been possible to make theneutralization reaction more intense and con- H sequently to shorten theperiod of contact between the oil and lye by pretreating the lye to therefining temperaateint O ment of the apparatus according to theinvention.

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ture and causing increased turbulence of the reaction mixture during thepassage through said rotating chamber. In this way, it has been possibleto use a contact time of less than 0.5 second. Preferably, a contacttime of 0.1 second or less, for example 0.05 second, is used.Furthermore, it has been found advantageous to preheat the oil as wellas the lye to a temperature of at least C., preferably about to C. Thestrength of the lye may vary according to the acidity of the oil to beneutralized and may, for instance, be 35 N. This relatively hightemperature increases the velocity of the neutralization reaction,counteracts formation of emulsion, and facilitates the separation due toreduced viscosity.

The invention also includes apparatus for carrying out the presentmethod. This apparatus comprises a centrifuge as described above, whichcentrifuge is modified by providing turbulence-producing passages forthe oil-reagent mixture in the feed chamber. According to the preferredembodiment, these passages are formed by providing discs in the feedchamber perpendicular to its axis of rotation and spaced at intervalsalong said axis, each of the discs forming openings displaced inrelation to corresponding openings in adjacent discs, reckoned in theaxial direction. The discs can advantageously be supported by a rodextending coaxially through the feed chamber from the inner end of thehollow spindle and fixed at this end, for instance by means of a capsupporting the rod and screwed onto the inner end of the spindle. Thisrod and the discs form together an easily detachable sub-assemblylocated in the immediate vicinity of the openings through which theoil-reagent mixture discharges from the feed chamber and is supplied tothe separating chamber of the centrifuge.

The accompanying drawings show a preferred embodithe drawings,

Fig. l is a vertical sectional view of the apparatus,

Fig. 2 is a similar view, on a larger scale, of the uppermost part ofthe hollow spindle with the centrifugal bowl mounted thereon;

Fig. 3 is a horizontal sectional view on line IIIIII in Fig. 2;

Fig. 4 is a vertical sectional view of the lowermost part of theapparatus, including oil and lye supply means, and

Fig. 5 is a sectional view along line V-V in Fig. 4.

Referring to the drawings, the apparatus comprises pipes or supply means1 and 2 for oil and lye, respectively. As best shown in Figs. 4 and 5,the oil pipe 1 communicates with a hollow spindle 3 and the lye pipe 2communicates with a stationary tube 4 which is fitted in and is coaxialwith the hollow spindle 3. The tube 4 is best shown in Figs. 2 and 4.The hollow spindle 3 is double-journalled in the bearing housings 5 and6 and is driven by driving means including a worm wheel 7 and a worm 8.On the spindle 3., above the bearing housing 5, is mounted a centrifugalbowl 9 of common design, which is surrounded by a housing 10. The oiland the soap are discharged separately through the outlets 11 and 12,respectively.

The hollow spindle 3 (Fig. 2) is supported laterally in the upperbearing housing by the bearing assembly 5a, which is yieldingly centeredin the housing by radial springs, one of which is shown at 5b. Thestationary tube 4 terminates at its upper end a short distance below aseries of discs 13 which are located in and rotate with the hollowspindle. These discs are arranged a short distance below the supplyopenings 14 of the bowl 9. The discs 13 are spaced from each other alongthe axis of the hollow spindle 3 and are disposed horizontally, that is,in planes at right angles to this axis.

Each disc 13 fits closely in the spindle 3 but is provided with twoopposite segment-shaped openings 15 which form passages for the mixtureof oil and lye, as best shown in Fig. 3. The discs 13 are all secured toa central rod 16 on which they are placed in such relation to each otherthat the mixture of oil and lye cannot pass through the disc openings 15in a linear path. In the embodiment shown, the segment-shaped openings15 in alternate discs 13 are displaced 90 from the correspondingopenings 15' in the other discs. The rod 16 is supported at its upperend by a cap 14:: screwed on the upper end of the spindle and formingthe openings 14.

In Fig. 4, I have shown on a large scale the journalling of the hollowspindle 3 in the lower bearing housing 6. The hollow spindle 3 isrotatable in the bearing 17 and is provided with a seal 18, while thetube 4 is held stationary in the hollow spindle 3 by means of a fitting19. The central channel 20 of the tube 4 communicates with the lyesupply means 2 by way of channels 21 in the fitting 19. An extension Inof the oil pipe is fixed in surrounding relation to the reagent tube 4and forms therewith an oil passage.

It will be understood that the stream of lye discharges from the upperend of tube 4 into the surrounding oil stream flowing upward throughhollow spindle 3, and the oil and lye are then immediately mixedtogether as they fiow upward through the turbulence-producing passagesformed by the discs 13. The mixture then passes promptly through theopenings 14 into the separating chamber of bowl 9, where it is rapidlyseparated into oil and soap. Due to the back pressure on the materialfed into the bowl 9, the rotating sub-chamber containing the discs 13 iskept completely filled with oil and lye during the feeding. Thissub-chamber forms in effect a rotating feed chamber opening directlyinto the separating chamber of the bowl 9. The sealing collar 18 formsan hermetically sealed flow passage between the stationary oil supplypipe 1 and the outer portion of the rotating hollow spindle 3 of thebowl.

The significance of the present method is illustrated in the followingexamples, in which the temperature of the oil and lye (caustic soda) wasabout 94 C. and the lye was used in an excess of about 20% of the amountnecessary to neutralize the free fatty acids of the oil.

Example 1 Palm oil having a free fatty acid content of 3.5% wasneutralized with lye of 4.5 N. After the separation the refining losswas 5.3% and the oil had a free fatty acid content of 0.05%.

Example 2 Soya bean oil having a free fatty acid content of 0.78% wasneutralized with lye of 3.5 N. After the separation the refining losswas 1.1% and the oil had a free fatty acid content of 0.06%.

Example 3 Lard (white hog grease) having a free fatty acid content of5.2% was neutralized with lye of 4.3 N. After the separation therefining loss was 7.8% and the oil had a free fatty acid content of0.08%.

Example 4 Cocoanut oil having a free fatty acid content of 4.3% wasneutralized with lye of 2.4 N. After the separation the refining losswas 5.8% and the oil had a free fatty acid content of 0.04%.

I claim:

1. In the neutralization of fatty oils in a centrifuge by feedingseparate streams of oil and aqueous alkali lye, respectively, into arotating feed chamber forming a zone 4 of relatively low centrifugalforce within the centrifuge, keeping said feed chamber filled with oiland lye during said feeding, the lye being led directly into and mixedwith the oil mass rotating with said chamber, feeding the resultingmixture into a zone of relatively high centrifugal force formed by theseparating chamber of said centrifuge to divide it into oil and soap,and separately discharging the oil and soap from said centrifuge, theimprovement which comprises substantially heating at least the oil priorto the neutralization, passing the oillye mixture, during a period oftime of less than a second, in turbulence-producing passages throughsaid rotating feed chamber, and feeding said mixture immediately fromsaid last chamber to the separating chamber.

2. The improvement according to claim 1, in which the oil and the lyeare both heated to a temperature of about to C. prior to saidneutralization.

3. The improvement according to claim 1, in which the oil-lye mixture ispassed through said rotating feed chamber within a period of time lessthan 0.5 second.

4. The improvement according to claim 1, in which the oil-lye mixture ispassed through said rotating feed chamber within a period of time in theorder of 0.1 second.

5. In a centrifuge comprising a centrifugal bowl rotatable on a verticalaxis and having a separating chamber provided with separate outlets foroil and neutralization products, respectively, a hollow spindleextending from the bowl and forming a rotating feed chamber openingdirectly into the separating chamber, a fixed reagent supply tubeextending through the hollow spindle into the feed chamber, an oilsupply pipe fixed in surrounding relation to the reagent tube andforming therewith an oil passage, and means forming an hermeticallysealed passage between the oil supply pipe and the outer portion of thebowl spindle, the improvement comprising means in said feed chamberforming turbulence-producing passages for the oil-reagent mixture.

6. A centrifuge according to claim 5, in which said turbulence-producingmeans include discs disposed perpendicularly to the axis of rotation ofsaid feed chamber and spaced from each other along said axis, each ofsaid discs forming openings displaced angularly in relation tocorresponding openings in adjacent discs.

7. A centrifuge according to claim 5, in which said turbulence-producingmeans include discs disposed perpendicularly to the axis of rotation ofsaid feed chamber and spaced from each other along said axis, each ofsaid discs forming openings displaced angularly in relation tocorresponding openings in adjacent discs, and a rod extending axiallythrough the feed chamber from the upper end of the hollow spindle and,supporting discs.

8. A centrifuge according to claim 5, in which said turbulence-producingmeans include discs disposed perpendicularly to the axis of rotation ofsaid feed chamber and spaced from each other along said axis, each ofsaid discs forming openings displaced angularly in relation tocorresponding openings in adjacent discs, a rod extending axiallythrough the feed chamber and supporting the discs, and a cap supportingthe rod and secured to the upper end of the spindle, the cap forming anopening leading from said feed chamber to said separating chamber.

References Cited in the file of this patent UNITED STATES PATENTS542,756 Ekenberg July 16, 1895 791,496 Ponten June 6, 1905 2,182,755Clayton et al. Dec. 5, 1939 2,663,719 Ayres Dec. 22, 1953

1. IN THE NEUTRALIZATION OF FATTY OILS IN A CENTRIFUGE BY FEEDING SEPARATE STREAMS OF OIL AND AQUEOUS ALKALI LYE, RESPECTIVELY, INTO A ROTATING FEED CHAMBER FORMING A ZONE OF RELATIVELY LOW CENTRIFUGAL FORCE WITHIN THE CENTRIFUGE, KEEPING SAID FEED CHAMBER FILLED WITH OIL AND LYE DURING SAID FEEDING, THE LYE BEING LED DIRECTLY INTO AND MIXED WITH THE OIL MASS ROTATING WITH SAID CHAMBER, FEEDING THE RESULTING MIXTURE INTO A ZONE OF RELATIVELY HIGH CENTRIFUGAL FORCE FORMED BY THE SEPARATING CHAMBER OF SAID CENTRIFUGE TO DIVIDE IT INTO OIL AND SOAP, AND SEPARATELY DISCHARGING THE OIL AND SOAP FROM SAID CENTRIFUGE, THE IMPROVEMENT WHICH COMPRISES SUBSTANTIALLY HEATING AT LEAST THE OIL PRIOR TO THE NEUTRALIZATION, PASSING THE OILLYE MIXTURE, DURING A PERIOD OF TIME OF LESS THAN A SECOND, 